The general operation system of a steam valve for a coffee maker comprises a steam chamber 7, as shown in FIG. 1, which has a water inlet 71, a heater 72, a water outlet 73 and a filter 74. The water inlet 71 provides water into the steam chamber 7, and the water is heated and transformed into steam and flows through the water outlet 73 and the filter 74 into a container. A conventional coffee maker has a through hole 81 in a steam valve 8, as shown in FIG. 5, with a conical ring 82 at the middle portion thereof, and a valve block 83 underneath the conical ring 82. The steam valve 8 has a cap 85 at the lower portion, and a spring 84 seats between the valve block 83 and the cap 85. The spring 84 urges the valve block 83 against the conical ring 82 to block the through hole 81. The cap 85 has an axial through hole 851 and a transverse through hole 852 interconnected with the axial through hole 851. The transverse through hole 852 is connected outwardly. When a pressure is applied to push the valve block 83 downward, which opens the through hole 81, the axial through hole 851 and the transverse through hole 852, and steam is guided to flow through. Due to the conical shape of the valve block 83, the pushing force has to be strong enough in order to push the valve block 83. The steam may spread out in an unstable status and may even cause an accident of burning.
In view of this and many other shortcomings, the inventor has invented the present invention to make improvements.